1. Field of the Invention
The subject invention relates to fluid filtration devices, and more particularly, to a filter assembly having a keyed lockout system to ensure replacement cartridge compatibility.
2. Background of the Related Art
Commercial vending machines for dispensing liquids such as coffee or soft drinks are wide spread in our society. It is common to filter liquids such as water in these vending machines before they are dispensed by circulating the water through an appropriate filter. It is also commonplace to find filtering devices in consumer appliances such as refrigerators for filtering drinking water and for ice production. Commercial and domestic filtering devices of this type have a limited useful life and require frequent replacement. Examples of prior art replaceable filtering devices of this type are disclosed in commonly assigned U.S. Pat. No. 4,735,716 to Petrucci et al. and U.S. Pat. No. 4,806,240 to Giordano et al.
In most instances, the replaceable filters employed in commercial and consumer appliances are manufactured in accordance with particular design specifications and performance parameters provided by the appliance manufacturer. In many cases, the filter media used in such filters consists of a proprietary material or is manufactured using a proprietary process. Thus, appliance manufactures often recommend that replacement cartridges be purchased from the original equipment provider so as to ensure the integrity and proper operation of the filtering system.
Oftentimes, the owner of a household appliance or the maintenance personnel servicing a commercial vending machine is not aware of the replacement filter specifications and operating parameters of the filtering system. Consequently, they unknowingly jeopardize the integrity of the filtration system by replacing a used filter with an inferior or incompatible replacement filter supplied by an after-market manufacturer. This problem has also been encountered by automotive filter manufacturers, as inferior replacement fuel filters are frequently installed in a vehicle without the knowledge of the vehicle owner or operator.
One solution to this problem is disclosed in U.S. Pat. No. 5,035,797 to Janik, wherein a key system is provided to ensure replacement cartridge compatibility for axially mounted fuel filters with threaded retaining collars. The key system employs a unique matrix of axially projecting keys formed in a base for axially receiving a filter cartridge, and a corresponding matrix of slots formed in a compatible cartridge, so that for a given compatible cartridge and base, the keys are interlockable in the slots to securely lock the cartridge in the base. For each non-compatible cartridge and base, the base keys are not-mateable with the cartridge slots and interfere with the mounting of the cartridge to the base. A similar key system is disclosed in U.S. Pat. No. 5,186,829 to Janik which includes a set of angularly spaced arcuate projections that protrude radially from the cylindrical side wall of the fuel filter cartridge to mate with corresponding spaced apart recesses in the base when the cartridge is axially pushed into the base. U.S. Pat. No. 5,837,137 to Janik discloses yet another key system for an axially mounted fuel filter with a threaded retaining collar.
While such prior art key systems are suitable for use in conjunction with axially mountable automotive fuel filters having threaded retaining collars, they are not easily adapted for use in conjunction with consumer and industrial water filtration systems wherein the filter cartridge is provided with a set of cam lugs configured to facilitate rotatable mounting of the cartridge to a base or supporting structure. Examples of prior art filter cartridges having lugged engagement portions are disclosed in the Petrucci et al. and Giordano et al. patents discussed hereinabove, and in U.S. Pat. Nos. 4,857,189 and 4,956,086 to Thomsen et al. It would beneficial to provide a key system for replaceable filter cartridges having lugged mounting systems.